Problem: Simplify the following expression: $10\sqrt{45}$.
Explanation: First, try to factor a perfect square out of the radical. $= 10\sqrt{45}$ $= 10\sqrt{9 \cdot 5}$ Separate the radical and simplify. $= 10\sqrt{9} \cdot \sqrt{5}$ $= 10 \cdot 3 \cdot \sqrt{5}$ $= 30\sqrt{5}$